This disclosure relates generally to bone fixation implants, and in particular relates to a bone plate that is configured to lockingly receive a bone screw at an angular orientation in a range of permissible angular orientations at which the bone plate can lockingly receive the bone screw.
When bones are damaged through trauma, disease, distraction osteogenesis, or orthognathic surgery, the defect is typically reduced, and bone fixation plates are commonly applied to the bone on opposite sides of the defect to ensure union in the desired position. Bone plates are typically made from a rigid material, such as titanium, and include fixation holes that are sized to be driven through the fixation holes and into the underlying bone to secure the bone plate to the bone. One common bone screw used in such application is generally referred to as a compression screw. Compression screws have unthreaded heads and threaded shafts. Accordingly, the compression screw can be driven through the plate fixation hole and into the underlying bone until the head applies a compression force against the bone plate toward the underlying bone. Another common bone screw used in such applications is generally referred to as a locking screw. Locking screws have threaded heads and threaded shafts. Accordingly, the locking screw can be driven through the plate fixation hole and into the underlying bone until the head threadedly mates with the bone plate in the fixation hole. Thus, the head of the locking screw does not apply a compressive force against the bone plate toward the underlying bone.
Conventionally, locking screws were inserted through the screw hole along the central screw hole axis in order to ensure that the threaded screw head mates with the plate in the threaded fixation hole. Recently, however, bone plates have been developed having threaded fixation holes that are configured to receive locking screws at different trajectories within a range of trajectories whereby the bone plate threadedly mates with the locking screw head in the threaded hole. While bone plates having such holes, commonly referred to as variable angle holes, have proved to be satisfactory for their intended purpose, improved variable angle holes are nevertheless desired.